Dedicated diversity and inclusion programs are important tools to utilize in a successful organization. Cross-disciplinary studies show that diversity contributes positively to overall productivity and innovation, in both profit and non-profit sectors. Diverse working groups are capable of producing better science, and creating an inclusive environment is essential to maintaining diversity in the workplace. <p> </p>This paper first outlines studies of the measured benefits of diversity, and the different ways in which they manifest, in order to emphasize its importance. Demographics data from international astronomy organizations is presented to illustrate the current state of the workforce in observatories and within observatory operations. Finally, a much-needed focus is placed on inclusion in the workplace. We review why creating an inclusive environment is important for the success of maintaining a diverse organization. We discuss how different programs implemented at astronomical observatories contribute to creating an inclusive environment, and detail real-world examples of these efforts taking place in these institutions. The goal is that these strategies can be adapted to benefit other similar organizations.

With the advent of large-scale time-domain surveys such as the LSST, there is a strong desire for the 4-m SOAR Telescope to be able to respond efficiently and effectively to transient alerts. Enabling the required capabilities at SOAR will also support a greater variety of science programs than conventional telescope scheduling. These capabilities are best deployed with SOAR acting as one of several telescopes responding to alerts and supporting time domain programs. We outline how this might be done if SOAR is included as a node in the Las Cumbres Observatory network, at least part-time. This allows SOAR to make use of extensive existing software infrastructure, while adding a larger aperture to the existing network. Participation of SOAR also serves as a pathfinder for participation of other large telescopes in an evolved LCO network. The overall workflow is outlined. Required interfaces are described. Finally, the initial development efforts with this goal in mind are outlined.

The CHARA array is an optical/near infrared interferometer consisting of six 1-meter diameter telescopes, the longest baseline of which is 331 meters. With sub-millisecond angular resolution, the CHARA array is able to spatially resolve nearby stellar systems and reveal their detailed structures. To improve the sensitivity and scientific throughput, the CHARA array was funded by NSF-ATI in 2011 for an upgrade of adaptive optics (AO) systems to all six telescopes. This first grant covered Phase I of the adaptive optics system, which includes an on-telescope Wavefront Sensor (WFS) and non-common-path (NCP) error correction. Phase II of the program was funded by the NSF/MRI in 2016, and includes purchasing and installing the deformable mirrors at each telescope to complete the system. In this paper we will discuss both phases of the program, how the challenge of AO differs for interferometry, and the first results of the full system.

The CHARA Array is a six-element, optical/NIR interferometer, which currently has the largest operational baselines in the world. The Array is operated by Georgia State University and is located at the Mount Wilson Observatory in California. The Array thrives thanks to members of the CHARA consortium that includes LESIA (Observatoire de Paris), Observatoire de la Cote dAzur, University of Michigan, Sydney University, Australian National University, and University of Exeter. Here we give a brief introduction to the Array infrastructure with a focus on a developing Adaptive Optics (AO) program, the new community access program funded by the NSF, and recent science results.

The Planet Formation Imager (PFI) is a near- and mid-infrared interferometer project with the driving science goal of imaging directly the key stages of planet formation, including the young proto-planets themselves. Here, we will present an update on the work of the Science Working Group (SWG), including new simulations of dust structures during the assembly phase of planet formation and quantitative detection efficiencies for accreting and non-accreting young exoplanets as a function of mass and age. We use these results to motivate two reference PFI designs consisting of a) twelve 3m telescopes with a maximum baseline of 1.2km focused on young exoplanet imaging and b) twelve 8m telescopes optimized for a wider range of young exoplanets and protoplanetary disk imaging out to the 150K H<sub>2</sub>O ice line. Armed with 4 x 8m telescopes, the ESO/VLTI can already detect young exoplanets in principle and projects such as MATISSE, Hi-5 and Heimdallr are important PFI pathfinders to make this possible. We also discuss the state of technology development needed to make PFI more affordable, including progress towards new designs for inexpensive, small field-of-view, large aperture telescopes and prospects for Cubesat-based space interferometry.

The Operations Simulator was used to prototype the Large Synoptic Survey Telescope (LSST) Scheduler. Currently, the Scheduler is being developed separately to interface with the LSST Observatory Control System (OCS). A new Simulator is under concurrent development to adjust to this new architecture. This requires a package simulating enough of the OCS to allow execution of realistic schedules. This new package is called the Simulated OCS (SOCS). In this paper we detail the SOCS construction plan, package structure, LSST communication middleware platform use, provide some interesting use cases that the separated architecture allows and the software engineering practices used in development.

The CHARA Array, operated by Georgia State University, is located at Mount Wilson Observatory just north of Los Angeles in California. The CHARA consortium includes many groups, including LIESA in Paris, Observatoire de la Cote d’Azur, the University of Michigan, Sydney University, the Australian National University, the NASA Exoplanet Science Institute, and most recently the University of Exeter. The CHARA Array is a six-element optical/NIR interferometer, and for the time being at least, has the largest operational baselines in the world. In this paper we will give a brief introduction to the array infrastructure with a focus on our Adaptive Optics program, and then discuss current funding as well as opportunities of funding in the near future.

The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to ~100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs.

The NOAO Data Lab aims to provide infrastructure to maximize community use of the high-value survey datasets now being collected with NOAO telescopes and instruments. As a science exploration framework, the Data Lab allow users to access and search databases containing large (i.e. terabyte-scale) catalogs, visualize, analyze, and store the results of these searches, combine search results with data from other archives or facilities, and share these results with collaborators using a shared workspace and/or data publication service. In the process of implementing the needed tools and services, specific science cases are used to guide development of the system framework and tools. The result is a Year-1 capability demonstration that (fully or partially) implements each of the major architecture components in the context of a real-world science use-case. In this paper, we discuss how this model of science-driven development helped us to build a fully functional system capable of executing the chosen science case, and how we plan to scale this system to support general use in the next phase of the project.

Collaborative research/computing environments are essential for working with the next generations of large astronomical data sets. A key component of them is a distributed storage system to enable data hosting, sharing, and publication. VOSpace<sup>1</sup> is a lightweight interface providing network access to arbitrary backend storage solutions and endorsed by the International Virtual Observatory Alliance (IVOA). Although similar APIs exist, such as Amazon S3, WebDav, and Dropbox, VOSpace is designed to be protocol agnostic, focusing on data control operations, and supports asynchronous and third-party data transfers, thereby minimizing unnecessary data transfers. It also allows arbitrary computations to be triggered as a result of a transfer operation: for example, a file can be automatically ingested into a database when put into an active directory or a data reduction task, such as Sextractor, can be run on it. In this paper, we shall describe the VOSpace implementations that we have developed for the NOAO Data Lab. These offer both dedicated remote storage, accessible as a local file system via FUSE, and a local VOSpace service to easily enable data synchronization.

The Arizona-NOAO Temporal Analysis and Response to Events System (ANTARES) is a joint effort of NOAO and the Department of Computer Science at the University of Arizona to build prototype software to process alerts from time-domain surveys, especially LSST, to identify those alerts that must be followed up immediately. Value is added by annotating incoming alerts with existing information from previous surveys and compilations across the electromagnetic spectrum and from the history of past alerts. Comparison against a knowledge repository of properties and features of known or predicted kinds of variable phenomena is used for categorization. The architecture and algorithms being employed are described.

We describe a back-end Adaptive Optics system for the CHARA Array called Lab-AO intended to compensate for non-common path errors between the AO system at the telescopes and the final beam combining area some hundreds of meters away. The system is an on-axis, very small field of view, low order system that will work on star light if enough is present, or will make use of a blue light beacon sent from the telescope towards the laboratory if not enough star light is available. The first of six of these system has been installed and has recently been tested on the sky. Another five will be built for the remaining telescopes later this year.

The Operations Simulator for the Large Synoptic Survey Telescope (LSST; http://www.lsst.org) allows the planning of LSST observations that obey explicit science driven observing specifications, patterns, schema, and priorities, while optimizing against the constraints placed by design-specific opto-mechanical system performance of the telescope facility, site specific conditions as well as additional scheduled and unscheduled downtime. It has a detailed model to simulate the external conditions with real weather history data from the site, a fully parameterized kinematic model for the internal conditions of the telescope, camera and dome, and serves as a prototype for an automatic scheduler for the real time survey operations with LSST. The Simulator is a critical tool that has been key since very early in the project, to help validate the design parameters of the observatory against the science requirements and the goals from specific science programs. A simulation run records the characteristics of all observations (e.g., epoch, sky position, seeing, sky brightness) in a MySQL database, which can be queried for any desired purpose. Derivative information digests of the observing history are made with an analysis package called Simulation Survey Tools for Analysis and Reporting (SSTAR). Merit functions and metrics have been designed to examine how suitable a specific simulation run is for several different science applications. Software to efficiently compare the efficacy of different survey strategies for a wide variety of science applications using such a growing set of metrics is under development. A recent restructuring of the code allows us to a) use "look-ahead" strategies that avoid cadence sequences that cannot be completed due to observing constraints; and b) examine alternate optimization strategies, so that the most efficient scheduling algorithm(s) can be identified and used: even few-percent efficiency gains will create substantive scientific opportunity. The enhanced simulator is being used to assess the feasibility of desired observing cadences, study the impact of changing science program priorities and assist with performance margin investigations of the LSST system.

The LSST will, over a 10-year period, produce a multi-color, multi-epoch survey of more than
18000 square degrees of the southern sky. It will generate a multi-petabyte archive of images and
catalogs of astrophysical sources from which a wide variety of high-precision statistical studies can
be undertaken. To accomplish these goals, the LSST project has developed a suite of modeling and
simulation tools for use in validating that the design and the as-delivered components of the LSST
system will yield data products with the required statistical properties. In this paper we describe the
development, and use of the LSST simulation framework, including the generation of simulated
catalogs and images for targeted trade studies, simulations of the observing cadence of the LSST, the
creation of large-scale simulations that test the procedures for data calibration, and use of end-to-end
image simulations to evaluate the performance of the system as a whole.

We describe the Metrics Analysis Framework (MAF), an open-source python framework developed to provide a user-friendly, customizable, easily-extensible set of tools for analyzing data sets. MAF is part of the Large Synoptic Survey Telescope (LSST) Simulations effort. Its initial goal is to provide a tool to evaluate LSST Operations Simulation (OpSim) simulated surveys to help understand the effects of telescope scheduling on survey performance, however MAF can be applied to a much wider range of datasets. The building blocks of the framework are Metrics (algorithms to analyze a given quantity of data), Slicers (subdividing the overall data set into smaller data slices as relevant for each Metric), and Database classes (to access the dataset and read data into memory). We describe how these building blocks work together, and provide an example of using MAF to evaluate different dithering strategies. We also outline how users can write their own custom Metrics and use these within the framework.

The reviewers of our first NSF proposal asked us to prepare a more ambitious plan, and we did. When it was funded, the scope of the resources made available was far below the scope of the project. What to do? The only way to proceed within budget was to eliminate the entire professional engineering component of the proposal team, and we did so. This left the CHARA staff and a few consultants. The story of building the CHARA Array is largely the story of how to build a facility and instrument with no engineers, no managers, and no meetings. How was this possible?

We initiated a multi-technique campaign to understand the physics and properties of the massive binary system MWC 314. Our observations included optical high-resolution spectroscopy and Johnson photometry, nearinfrared spectrophotometry, and <i>K′</i>−band long-baseline interferometry with the CHARA Array. Our results place strong constraints on the spectroscopic orbit, along with reasonable observations of the phase-locked photometric variability. Our interferometry, with input from the spectrophotometry, provides information on the geometry of the system that appears to consist of a primary star filling its Roche Lobe and loosing mass both onto a hidden companion and through the outer Lagrangian point, feeding a circumbinary disk. While the multi-faceted observing program is allowing us to place some constraints on the system, there is also a possibility that the outflow seen by CHARA is actually a jet and not a circumbinary disk.

This discussion, the first of three describing how the CHARA Array came to be, focuses on the establishment of the Center for High Angular Resolution Astronomy at Georgia State University, our site selection saga, and some apparently brilliant decisions stumbled into. The technical and scientific achievements of the CHARA Array to date are far more than just an argument for perseverance. CHARA's success stands upon audacity, risk taking, luck, and, above all else, a core team of wonderfully talented and dedicated individuals who made it all turn out well.

Among the most fascinating and hotly-debated areas in contemporary astrophysics are the means by which planetary systems are assembled from the large rotating disks of gas and dust which attend a stellar birth. Although important work has already been, and is still being done both in theory and observation, a full understanding of the physics of planet formation can only be achieved by opening observational windows able to directly witness the process in action. The key requirement is then to probe planet-forming systems at the natural spatial scales over which material is being assembled. By definition, this is the so-called Hill Sphere which delineates the region of influence of a gravitating body within its surrounding environment. The Planet Formation Imager project (PFI; http://www.planetformationimager.org) has crystallized around this challenging goal: to deliver resolved images of Hill-Sphere-sized structures within candidate planethosting disks in the nearest star-forming regions. In this contribution we outline the primary science case of PFI. For this purpose, we briefly review our knowledge about the planet-formation process and discuss recent observational results that have been obtained on the class of transition disks. Spectro-photometric and multi-wavelength interferometric studies of these systems revealed the presence of extended gaps and complex density inhomogeneities that might be triggered by orbiting planets. We present detailed 3-D radiation-hydrodynamic simulations of disks with single and multiple embedded planets, from which we compute synthetic images at near-infrared, mid-infrared, far-infrared, and sub-millimeter wavelengths, enabling a direct comparison of the signatures that are detectable with PFI and complementary facilities such as ALMA. From these simulations, we derive some preliminary specifications that will guide the array design and technology roadmap of the facility.

The CHARA Array has been a PI led, low budget, and low manpower operation, and has followed a fairly unconventional path in its development. In this, the third paper of a series of three, we discuss some of the engineering and design decisions made along the way, some right and some wrong, with a focus on the choice between in-house development and the purchase of pre-built, or sub-contracted, subsystems. Along with these issues we will also address a few parts of the system that we might have done differently given our current knowledge, and those that somehow turned out very well.

Complex non-linear and dynamic processes lie at the heart of the planet formation process. Through numerical simulation and basic observational constraints, the basics of planet formation are now coming into focus. High resolution imaging at a range of wavelengths will give us a glimpse into the past of our own solar system and enable a robust theoretical framework for predicting planetary system architectures around a range of stars surrounded by disks with a diversity of initial conditions. Only long-baseline interferometry can provide the needed angular resolution and wavelength coverage to reach these goals and from here we launch our planning efforts. The aim of the &#80;lanet Formation Imager" (PFI) project is to develop the roadmap for the construction of a new near-/mid-infrared interferometric facility that will be optimized to unmask all the major stages of planet formation, from initial dust coagulation, gap formation, evolution of transition disks, mass accretion onto planetary embryos, and eventual disk dispersal. PFI will be able to detect the emission of the cooling, newlyformed planets themselves over the first 100 Myrs, opening up both spectral investigations and also providing a vibrant look into the early dynamical histories of planetary architectures. Here we introduce the Planet Formation Imager (PFI) Project (www.planetformationimager.org) and give initial thoughts on possible facility architectures and technical advances that will be needed to meet the challenging top-level science requirements.

The CHARA array is an optical interferometer with six 1-meter diameter telescopes, providing baselines from 33 to 331 meters. With sub-milliarcsecond angular resolution, its versatile visible and near infrared combiners offer a unique angle of studying nearby stellar systems by spatially resolving their detailed structures. To improve the sensitivity and scientific throughput, the CHARA array was funded by NSF-ATI in 2011 to install adaptive optics (AO) systems on all six telescopes. The initial grant covers Phase I of the AO systems, which includes on-telescope Wavefront Sensors (WFS) and non-common-path (NCP) error correction. Meanwhile we are seeking funding for Phase II which will add large Deformable Mirrors on telescopes to close the full AO loop. The corrections of NCP error and static aberrations in the optical system beyond the WFS are described in the second paper of this series. This paper describes the design of the common-path optical system and the on-telescope WFS, and shows the on-sky commissioning results.

The Large Synoptic Survey Telescope will record approximately 2.5x10^6 images over a 10-year interval, using 6
optical filters, with a wide variety of cadences on time scales of seconds to years. The observing program will be of a
complexity that it can only be realized with heavily automated scheduling. The LSST OpSim team has devised a
schedule simulator to support development of that capability. This paper addresses the complex problem of how to
measure the success of a schedule simulation for realization of science objectives. Tools called Merit Functions evaluate
the patterns and other properties of scheduled image acquisitions.

The CHARA Array is a six telescope optical/IR interferometer run by the Center for High Angular Resolution
Astronomy of Georgia State University and is located at Mount Wilson Observatory just to the north of Los Angeles
California. The CHARA Array has the largest operational baselines in the world and has been in regular use for
scientific observations since 2004. In 2011 we received funding from the NSF to begin work on Adaptive Optics for our
six telescopes. Phase I of this project, fully funded by the NSF grant, consists of designing and building wavefront
sensors for each telescope that will also serve as tip/tilt detectors. Having tip/tilt at the telescopes, instead of in the
laboratory, will add several magnitudes of sensitivity to this system. Phase I also includes a slow wavefront sensor in the
laboratory to measure non-common path errors and small deformable mirrors in the laboratory to remove static and
slowly changing aberrations. Phase II of the project will allow us to place high-speed deformable mirrors at the
telescopes thereby enabling full closed loop operation. We are currently seeking funding for Phase II. This paper will
describe the scientific rational and design of the system and give the current status of the project.

In this paper, we review the current performance of the VEGA/CHARA visible spectrograph and make a review of
the most recent astrophysical results. The science programs take benefit of the exceptional angular resolution, the
unique spectral resolution and one of the main features of CHARA: Infrared and Visible parallel operation. We
also discuss recent developments concerning the tools for the preparation of observations and important features
of the data reduction software. A short discussion of the future developments will complete the presentation,
directed towards new detectors and possible new beam combination scheme for improved sensitivity and imaging
capabilities.

We present the results of the fifth Interferometric Imaging Beauty Contest. The contest consists in blind imaging of test data sets derived from model sources and distributed in the OIFITS format. Two scenarios of imaging with CHARA/MIRC-6T were offered for reconstruction: imaging a T Tauri disc and imaging a spotted red supergiant. There were eight different teams competing this time: Monnier with the software package MACIM; Hofmann, Schertl and Weigelt with IRS; Thiebaut and Soulez with MiRA ; Young with BSMEM; Mary and Vannier with MIROIRS; Millour and Vannier with independent BSMEM and MiRA entries; Rengaswamy with an original method; and Elias with the radio-astronomy package CASA. The contest model images, the data delivered to the contestants and the rules are described as well as the results of the image reconstruction obtained by each method. These results are discussed as well as the strengths and limitations of each algorithm.

The CHARA Array is a six-telescope optical/IR interferometer managed by the Center for High Angular Resolution
Astronomy of Georgia State University and located at Mount Wilson Observatory in the San Gabriel Mountains
overlooking Pasadena, California. The CHARA Array has the longest operational baselines in the world and has been in
regular use for scientific observations since 2005. In this paper we give an update of instrumentation improvements,
primarily focused on the beam combiner activity. The CHARA Array supports seven beam combiners: CHARA
CLASSIC, a two-way high-sensitivity K/H/J band system; CLIMB, a three-way K/H/J open-air combiner; FLUOR, a
two-way K-band high-precision system; MIRC, a four/six-way H/K-band imaging system; CHAMP, a six-way K-band
fringe tracker; VEGA, a four-way visible light high spectral resolution system; and PAVO, a three-way visible light high
sensitivity system. We also present an overview of science results obtained over the last few years, including some recent imaging results.

The efficiency of the CHARA Array has proven satisfactory for a wide variety of scientific programs enabled by the
first-generation beam combination and detector systems. With multi-beam combination and more ambitious scientific
goals, improvements in throughput and efficiency will be highly leveraged. Engineering data from several years of
nightly operations are used to infer atmospheric characteristics and raw instrumental visibility in both classic optical and
single-mode fiber beam combiners. This information is the basis for estimates of potential gains that could be afforded
by the implementation of adaptive optics. In addition to the very important partial compensation for higher order
atmosphere-induced wavefront errors, the benefits include reduction of static and quasi-static aberrations, reduction of
residual tilt error, compensation for differential atmospheric refraction, and reduction of diffractive beam propagation
losses, each leading to improved flux throughput and instrumental visibility, and to associated gains in operability and
scientific productivity.

A survey program with multiple science goals will be driven by multiple technical requirements. On a ground-based
telescope, the variability of conditions introduces yet greater complexity. For a program that must be largely autonomous
with minimal dwell time for efficiency it may be quite difficult to foresee the achievable performance. Furthermore,
scheduling will likely involve self-referential constraints and appropriate optimization tools may not be available. The
LSST project faces these issues, and has designed and implemented an approach to performance analysis in its
Operations Simulator and associated post-processing packages. The Simulator has allowed the project to present detailed
performance predictions with a strong basis from the engineering design and measured site conditions. At present, the
Simulator is in regular use for engineering studies and science evaluation, and planning is underway for evolution to an
operations scheduling tool. We will describe the LSST experience, emphasizing the objectives, the accomplishments and
the lessons learned.

We present the laboratory demonstration of a very high-dynamic range imaging instrument FIRST (Fibered Imager foR
Single Telescope). FIRST combines the techniques for aperture masking and a single-mode fiber interferometer to
correct wavefront errors, which leads to a very high-dynamic range up to 106 around very near the central object (~ &lambda;/D)
at visible to near-infrared wavelengths. Our laboratory experiments successfully demonstrated that the original image
can be reconstructed through a pupil remapping system. A first on-sky test will be performed at the Lick Observatory 3-
m Shane telescope for operational tests in the summer of 2010.

The CHARA Array is a six-telescope optical/IR interferometer operated by the Center for High Angular Resolution
Astronomy of Georgia State University and is located at Mount Wilson Observatory just to the north of Los Angeles
California. The CHARA Array has the largest operational baselines in the world and has been in regular use for scientific
observations since 2004. In this paper we give an update of instrumentation improvements, primarily focused on the
beam combiner activity. The CHARA Array supports seven beam combiners: CHARA CLASSIC, a two-way high
sensitivity K/H/J band system; CLIMB, a three-way K/H/J open air combiner, FLUOR, a two-way K band high
precision system; MIRC, a four/six-way H/K band imaging system; CHAMP, a six way K band fringe tracker; VEGA, a
four way visible light high spectral resolution system; and PAVO, a three-way visible light high sensitivity system. The
paper will conclude with a review of science results obtained over the last few years, including our most recent imaging results.

While a premier technique for laboratory spectroscopy, Fourier transform (FT) spectroscopy has fallen into disuse in
astronomical applications. The speed of a FT spectroscopy is significantly less than that of a dispersive spectrograph
with an array detector due to multiplex disadvantage. However, there are a number of advantages of the FT technique
that can be exploited to offer spectroscopic capabilities that would otherwise not be available. For very large telescopes
these include spectral resolutions significantly in excess of 100000 and 2-D spectral spatial imaging. By using postdispersers
with array detectors the speed difference between cryogenic grating and FT spectrographs can be reduced. We
explore the possibilities of using pre-existing FT equipment upgraded with modern detectors on next generation
telescopes. For specificity, we will adopt as our model FTS at the 4-m Mayall telescope and study how it could be
adapted to an ELT, and with what resulting performance.

The Pupil-mapping Exoplanet Coronagraphic Observer (PECO) mission concept uses a coronagraphic 1.4-m
space-based telescope to both image and characterize extra-solar planetary systems at optical wavelengths.
PECO delivers 10<sup>-10</sup> contrast at 2 &lambda;/D separation (0.15") using a high-performance Phase-Induced Amplitude
Apodization (PIAA) coronagraph which remaps the telescope pupil and uses nearly all of the light coming into
the aperture. For exoplanet characterization, PECO acquires narrow field images simultaneously in 16 spectral
bands over wavelengths from 0.4 to 0.9 &mu;m, utilizing all available photons for maximum wavefront sensing and
sensitivity for imaging and spectroscopy. The optical design is optimized for simultaneous low-resolution spectral
characterization of both planets and dust disks using a moderate-sized telescope. PECO will image the habitable
zones of about 20 known F, G, K stars at a spectral resolution of R&asymp;15 with sensitivity sufficient to detect
and characterize Earth-like planets and to map dust disks to within a fraction of our own zodiacal dust cloud
brightness. The PIAA coronagraph adopted for PECO reduces the required telescope diameter by a factor of two
compared with other coronagraph approaches that were considered for Terrestrial Planet Finder Coronagraph
Flight Baseline 1, and would therefore also be highly valuable for larger telescope diameters. We report on
ongoing laboratory activities to develop and mature key PECO technologies, as well as detailed analysis aimed
at verifying PECO's wavefront and pointing stability requirement can be met without requiring development of
new technologies.

The efficiency of the CHARA Array has proven satisfactory for the scientific programs enabled by the first-generation
beam combination and detector systems. With multi-beam combination and more ambitious scientific goals,
improvements in throughput and efficiency will be highly leveraged. Engineering data from several years of nightly
operations are used to infer atmospheric characteristics and raw instrumental visibility in both classic optical and single-
mode fiber beam combiners. This information is the basis for estimates of potential gains that could be afforded by the
implementation of adaptive optics. This includes reduction of static and quasi-static aberrations, reduction of residual
tilt error, compensation for differential atmospheric refraction, reduction of diffractive beam propagation losses, each
leading to improved flux throughput and instrumental visibility, and to associated gains in operability and scientific
productivity.

The CHARA Array is a six telescope optical/IR interferometer run by the Center for High Angular Resolution
Astronomy of Georgia State University (GSU) and is located at Mount Wilson Observatory just to the north of Los
Angeles, California. The CHARA Array has the largest operational baselines in the world and has been in regular use for
scientific observations since 2004. In this paper we give an update of instrumentation improvements, primarily focused
on the beam combiner activity. The CHARA Array supports seven beam combiners: CHARA CLASSIC, a two way
high sensitivity K/H band system; CLIMB, an upgrade to CLASSIC that includes closure phase measurements; FLUOR,
a two way K band high precision system; MIRC, a six way H/K band imaging system; CHAMP, a six way K band fringe
tracker; VEGA, a 4 way visible light high spectral resolution system; and PAVO, a 3 way visible light high sensitivity
system. The paper will conclude with a brief review of some science results obtained over the last few years.

We report the first scientific results from the Michigan Infrared Combiner (MIRC), including the first resolved
image of a main-sequence star besides the Sun. Using the CHARA Array, MIRC was able to clearly resolve the
well-known elongation of Altair's photosphere due to centrifugal distortion, and was also able to unambiguously
image the effect of gravity darkening. In this report, we also show preliminary images of the interacting binary
&beta; Lyr and give an update of MIRC performance.

We describe the present status of the development of a very high-dynamic range, diffraction limited imaging instrument FIRST (Fibered Imager foR Single Telescope), among which goals is the detection of nearby extra-solar planets at visible to near-infrared wavelengths from the ground. We have started to develop a prototype system which consists of a number of novel designs such as a segmented micro mirror array and silicon micro machined single-mode fiber arrays. Furthermore, we have proposed to build a FIRST instrument for the CFHT, which will be complementary to high-dynamic range instruments developed for 8m class telescopes at near-infrared wavelengths.

We have obtained high resolution orbital data with the CHARA Array for the bright star 12 Persei, a resolved double-lined spectroscopic
binary, an example of a Separated Fringe Packet Binary. We describe the data reduction process involved. By using a technique we have developed of 'side-lobe verniering', we can obtain an improved precision in separation of up to 25 micro-arcsec along a given baseline. For this object we find a semi-major axis 0.3 of Barlow, Scarfe, and Fekel (1998) [BSF], but with an increased inclination angle. The revised masses are therefore almost 6% greater than those of BSF. The overall accuracy in the masses is about 1.3%, now primarily limited by the spectroscopically determined radial velocities. The precision of the masses due to the interferometrically derived "visual" orbit alone is only about 0.2%. We expect that improved RVs and improved absolute calibration can bring down the mass errors to below 1%.

Observational modes in which simultaneous high spatial and spectral information are recovered, without the complexity and expense of a dispersed detection system, have been discussed for some time. Sometimes called Double Fourier/Spatio-Spectral Interferometry (DFSSI), these methods fuse the concepts of Fourier Transform Spectrometry with high spatial resolution interferometry. The basic underlying principle comes from the idea that different spectral components, yielding different fringe frequencies, can be separated out in the fringe spectrum for individual study. However in practice, seeing fluctuations have the effect of shifting and blurring together the fringe frequencies making it difficult to isolate discrete spectral components. DFSSI has not been widely exploited in astronomical interferometry, due in part to such considerations. Here we propose a closely-related, although distinct technique which is the analog of DFSSI implemented in the spatial (delay) space rather than the time (frequency) domain. We propose the name Double-Fourier Spatio-Spectral Decoding to distinguish it from the latter. The technique relies on careful calibration of the fringe envelope shape, which is a function of the shape of the overall bandpass of the interferometer. We show that for astrophysical systems with interesting variations in spatial structure for neighboring spectral regions (such as stars with emission-line winds) that it is possible to untangle separate spatial and spectral components without a multi-channel dispersed fringe detector. The principle has been demonstrated successfully with observations of the prototype emission-line object P Cygni
at the CHARA array.

Georgia State University's Center for High Angular Resolution Astronomy (CHARA) operates a multi-telescope, long-baseline, optical/infrared interferometric array on Mt. Wilson, California. We present a brief update on the status of this facility along with summaries of the first scientific results from the Array.

Using the FLUOR beam-combiner installed at the CHARA Array (Mt. Wilson, CA), we have obtained highprecision visibility measurements of Vega, one of the prototypic debris-disk stars, known to be surrounded by a large amount of cold dust in a ring-like structure at 80-100 AU. The combination of short and long baselines has allowed us to separately resolve the stellar photosphere and the close environment of the star (less than 8 AU). Our observations show a significant deficit in square visibility at short baselines with respect to the expected visibility of a simple UD stellar model (&#916;<i>V</i><sup>2</sup> equal or equivalent to 2%), suggesting the presence of an extended source of emission around Vega. The sparse (u, v) plane coverage does not allow the discrimination between a point source and an extended circumstellar emission as the source of the extended emission. However, we show that the presence of a point-like source within the FLUOR field-of-view (1" in radius, i.e., 7.8 AU at the distance of Vega) is highly unlikely. The excess emission is most likely due to the presence of hot circumstellar dust in the inner part of Vega's debris disk, with a flux ratio of 1.29 plus or minus 0.19% between the integrated dust emission and the stellar photosphere. Complementing this result with archival photometric data in the near- and mid-infrared and taking into account a realistic photospheric model for the rapidly rotating Vega, we derive the expected physical properties of the circumstellar dust by modelling its Spectral Energy Distribution. The inferred properties suggest that the Vega system could be currently undergoing major dynamical perturbations.

An optical system capable of extremely high contrast imaging (about 10<sup>-10</sup>) at separations comparable to the
telescope's diffraction limit is critical for direct imaging of extrasolar terrestrial planets. The PIAA coronagraph
(Guyon 2003) based on pupil apodization by geometrical remapping of the flux in the pupil plane seems to be
especially adopted for the exoplanet imaging. Although this technique combines many of the advantages found
separately in other coronagraphs, two serious concerns remain unanswered: optics manufacturability and effects
of diffraction propagation. We describe here a hybrid PIAA/CPA (Classical Pupil Apodization) design in which
the apodization is shared between a remapping system (the main apodizer) and "classical" apodizers (auxillary
apodizers). In this scheme, optics become easier to manufacture and diffraction effects can be decreased to a
level consistent with a 10<sup>-10</sup> PSF contrast in a wide spectral band. We show how the parameters of hybrid
PIAA/CPA system can be optimized and present some results of optical testing for the high optical quality
prototype of PIAA coronagraph.

The Phase-Induced Amplitude Apodization Coronagraph (PIAAC) uses a lossless beam apodization, performed
by aspheric mirrors, to produce a high contrast PSF. This concept offers a unique combination of high throughput
(almost 100%), high angular resolution (&#955;/D), small inner working angle (IWA = 1.5 &#955;/D), excellent achromaticity
(the apodization is performed by geometric reflection on mirrors) and low sensitivity to pointing errors or
stellar angular diameter. These characteristics make the PIAAC an ideal choice for direct imaging of extrasolar
terrestrial planets (ETPs) from space. We quantify the performance of the PIAAC and other coronagraph designs
both in terms of "raw" coronagraphic performance (throughput, IWA etc...) and number of stars around
which extrasolar terrestrial planets (ETPs) can be observed. We also identify the fundamental performance limit
that can be achieved by coronagraphy, and show that no other coronagraph design is as close to this limit as the
PIAAC. We find that in the photon noise limited regime, a 4m telescope with a PIAA coronagraph is able to
detect Earth-like planets around 30 stars with 1hr exposure time per target (assuming 25% throughput and exozodi
levels similar to our solar system). With a smaller 1 to 2-m diameter telescope, more massive rocky planets
could be detected in the habitable zones of a few nearby stars, and an imaging survey of Jupiter-like planets
could be performed. Laboratory results and detailed simulations confirm the large potential of this concept for
direct imaging of ETPs. A prototype high contrast PIAAC system is currently being operated to demonstrate
the coronagraph's performance.

The Mauna Kea Observatory offers a unique opportunity to build a large and sensitive interferometer. Seven telescopes have diameters larger than 3 meters and are or may be equipped with adaptive optics systems to correct phase perturbations induced by atmospheric turbulence. The maximum telescope separation of 800 meters can provide an angular resolution as good as 0.25 milli-arcseconds in the J band. The large pupils and long baselines make 'OHANA very complementary to existing large optical interferometers. From an astrophysical point of view, it opens the way to imaging of the central part of faint and compact objects such as active galactic nuclei and young stellar objects. On a technical point of view, it opens the way to kilometric or more arrays by propagating light in single-mode fibers. First instruments have been built and tested successfully at CFHT, Keck I and Gemini to inject light into single-mode fibers thus partly completing Phase I of the project. Phase II is now on-going with the prospects of the first combinations of Keck I - Keck II in 2004 and Gemini - CFHT in 2005.

Georgia State University's Center for High Angular Resolution Astronomy (CHARA) operates a multi-telescope, long-baseline, optical/infrared interferometric array on Mt. Wilson, California. We present an update on the status of this facility along with a sample of preliminary results from current scientific programs.

Amplitude apodization of a telescope's pupil can be used to reduce the diffraction rings (Airy rings) in the PSF to allow high contrast imaging. Rather than achieving this apodization by selectively removing light at the edges of the pupil, we propose to produce the desired apodized pupil by redistributing the pupil's light. This lossless apodization concept can yield a high contrast PSF which allows the efficient detection of Earth-sized planets around stars at ~10pc with a 2m visible telescope in space. We review the current status of a JPL-funded study of this concept for the Terrestrial Planet Finder (TPF) mission, including a lab experiment and extensive computer simulations.

The Extra-Solar Planetary Imager (ESPI) is envisioned as a space based, high dynamic range, visible imager capable of detecting Jovian like planets. Initially proposed as a NASA Midex (NASA/Medium Class Explorer) mission (PI:Gary Melnick), as a space-based 1.5 x 1.5 m2 Jacquinot apodized square aperture telescope. The combination of apodization and a square aperture telescope reduces the diffracted light from a bright central source increasing the planetary to stellar contrast over much of the telescope focal plane. As a result, observations of very faint astronomical objects next to bright sources with angular separations as small as 0.32 arcseconds become possible. This permits a sensitive search for exo-planets in reflected light. ESPI is capable of detecting a Jupiter-like planet in a relatively long-period orbit around as many as 160 to 175 stars with a signal-to-noise ratio > 5 in observations lasting maximally 100 hours per star out to ~16 parsecs. We discuss the scientific ramifications, an overview of the system design including apodizing a square aperture, signal to noise issues and the effect of wavefront errors and the scalability of ESPI with respect to NASA's Terrestrial Planet Finder mission.

The Extrasolar Planet Observatory (ExPO) is envisioned as a Discovery-class space telescope for the direct detection and characterization of extra-solar planets. ExPO would also demonstrate the feasibility of a number of technologies which could be critical to the ultimate success of the Terrestrial Planet Finder mission. ExPO would detect a wide range of planet types in the visible and near IR, and do spectrophotometry and spectroscopy on many of the detected objects. The apoodized square aperture coronagraphic space telescope is designed to resolve faint companions near much brighter point-like sources by achieving very high dynamic range imaging at separations as small as 0.1 arcsec.

Filled aperture telescopes can deliver a real, high Strehl image which is well suited for discrimination of faint planets in the vicinity of bright stars and against an extended exo-zodiacal light. A filled aperture offers a rich variety of PSF control and diffraction suppression techniques. Filled apertures are under consideration for a wide spectral range, including visible and thermal-IR, each of which offers a significant selection of biomarker molecular bands. A filled aperture visible TPF may be simpler in several respects than a thermal-IR nuller. The required aperture size (or baseline) is much smaller, and no cryogenic systems are
required. A filled aperture TPF would look and act like a normal telescope - vendors and users alike would be comfortable with its design and operation. Filled aperture telescopes pose significant challenges in production of large primary mirrors, and in very stringent wavefront requirements. Stability of the wavefront control, and hence of the PSF, is a major issue for filled aperture systems. Several groups have concluded that these and other issues can be resolved, and that filled aperture options are competitive for a TPF precursor and/or for the full TPF mission. Ball, Boeing-SVS and TRW have recently returned architecture reviews on filled aperture TPF concepts. In this paper, I will review some of the major considerations underlying these filled aperture concepts, and suggest key issues in a TPF Buyers Guide.

Once the proof of concept of the OHANA Array has been demonstrated, the Phase II capabilities can be put into regular science operation, and the OHANA facility can be upgraded to extend interferometric operation to include all of the telescopes of the OHANA Consortium member observatories. This will constitute the Phase III of OHANA. The technical developments required will be relatively straight-forward. Longer fiber sets will be procured (fiber losses are not a limiting factor at the OHANA scale). An enhanced delay line capability will be needed in order to exploit longer baselines with good sky coverage and ample super-synthesis (several compact, multi-pass long optical delay concepts are under investigation). The scheduling and operation modes of an instrument such as OHANA present interesting opportunities and complications. We envision a place for both collaborative consortium science, based on mutual allocation of facility access, and PI-driven access, based on telescope access exchange between consortium members. The most potentially successful mode of operation would imply a community driven model, open to proposals from the different time allocation comittees. This poster looks at possible methods of allocation and operation, inspired by the UKIRT infrared survey (UKIDSS), the European VLBI, and the very interesting possibility of a Mauna Kea telescope time exchange scheme. The issue of data property is of course intimately tied with the proposal/operation system, and means of data availability and distribution are discussed, along with data interpretation tools, which may be modeled on existing systems such as the ISC at Caltech or the JMMC in France. when weighed against the UV coverage, the potential science and the uniqueness of this project, all these issues are worth an in depth study. Discussions are starting as to an OHANA Operation Committee, the goal of which would be to discuss, define and eventually carry out operational modes. The goal, of course, is for the Operation Committee to handle the details of multi-telescope scheduling in a way that will be transparent to the scientist who merely seeks the observational results.

In this poster, we examine the science potential of an 800 meter interferometer such as the OHANA Array. The working assumptions are a K = 12 limiting magnitude, a 0.5 milliarcsecond resolution at K band, and a small (diffraction limit of individual telescope) field of view. The science cases described herein are by no means exhaustive and perhaps not even the ones that will eventually be carried out, but serve to illustrate the potential of the array. We expect that operation of the array will be proposal driven, so the actual science will come from the Mauna Kea communities. Our philosophy is that any measurement that can be made at a dedicated interferometer facility should not be a strong driver for OHANA. Therefore the science areas discussed in the poster focus on very high angular resolution measurements of faint sources. In some cases, science which can be addressed with simpler or dedicated facilities at an exploratory level can be carried to a significant new capability with OHANA. A limitng magnitude of 12 was obtained by simple computations, but first tests on the sky with the injection module (See adjacent poster on Phase I) will help narrow down this figure. At such sensitivity, Cepheid pulsations can be studied in considerable detail for a wide range of stellar parameters, leading to enhanced confidence in the accuracy of their use for distance measurement with minimal extrapolation or inferrence. The disk/star interaction zone in young stellar objects can be resolved with unprecedented detail for a range of masses and ages, providing direct information about the jet formation region, accretion rates and disk conditions. The broad line region of active galactic nuclei can be studied in a large number of sources of differing characteristics, testing specific models for AGN nuclear structure. For OHANA Phase III, a dual-star phase tracking capability is planned. With the resulting increased sensitivity, direct brown dwarf diameter measurement will provide a strong check on evolution models. Microlensing events could be resolved and provide unique new information about the lensing and the lensed objects.

The fibered beam combiner FLUOR, which has provided high accuracy
visibility measurements on the IOTA interferometer, is being moved to
the CHARA array which provides five 1m telescopes on baselines ranging from 35 to 330m. The combination CHARA/FLUOR makes it possible for the first time to achieve sub-milliarcsecond resolution in the K band, with a dynamic range of 100 or more.
We explore the scientific potential of CHARA/FLUOR, most notably in the domains of high contrast binaries and the characterization of Cepheid pulsations, and present some of the anticipated developements.

The 'OHANA (Optical Hawaiian Array for Nanoradian Astronomy, means "family" in Hawaiian) aims at making a large and sensitive optical/IR array with the Mauna Kea 3 to 10 meter telescopes. Telescopes will be linked with single-mode fibers to carry the coherence of the beams from the output of the telescopes adaptive optics systems to the beam combination units. The project has been divided into three phases. The first phase is dedicated to the injection of light into single-mode fibers and to the building of the injection module. The third phase is the realization of the complete array and its use by a wide community of astronomers. In the second phase, a prototype 'OHANA will be built and the "shortest" baselines will be explored. The baselines will be located in the South-East and West parts of the observatory. An extra baseline will possibly link the two groups of telescopes if infrastructure comply with it. This phase II 'OHANA will already be the longest and most sensitive optical/IR interferometer built. Scientific targets will span young stellar objects, extragalactic sources and other types of astronomical topics which require both high angular resolution and sensitivity. This paper reviews the main characteristics of the phase II interferometer.

Georgia State University's Center for High Angular Resolution Astronomy (CHARA) operates a multi-telescope, long-baseline, optical/infrared interferometric array on Mt. Wilson, California. Since its inception, one of the primary scientific goals for the CHARA Array has been the resolution of spectroscopic binary stars, which offer tremendous potential for the determination of fundamental parameters for stars (masses, luminosities, radii and effective temperatures). A new bibliographic catalog of spectroscopic binary orbits, including a calculated estimate of the anticipated angular separation of the components, has been produced as an input catalog in planning observations with the Array. We briefly describe that catalog, which will be made available to the community on the Internet, prior to discussing observations obtained with our 330-m baseline during the fall of 2001 of the double-lined spectroscopic systems &beta; Aur and &beta; Tri. We also describe the initial results of an inspection of the extrasolar planetary system &upsilon; And.

The CHARA Array consists of six 1-meter telescopes. The telescopes are at fixed positions laid out in a Y-shaped pattern, where the longest available baseline is 330 meters. The resolving power of this interferometric array operating at visible and short infrared wavelengths is better than one milli-arcsecond. The current infrared beam combination system is capable of combining the light from any two of the six telescopes in the array. With the existing infrared beam combination and detection system, we routinely observe in K and H band, where our magnitude limit is 6.

Individually resolved packets produced by scans from the CHARA Interferometer Array for binary stars can be analyzed in terms of the astrometry of the binary without using visibilities. We considered various methods for finding the locations of the packets, including autocorrelation and Shift-and-Add, but our best results were obtained from a method of direct packet fitting.
This method was put to use in analyzing two data sets each for the stars 12 Persei and Beta Arietis respectively. These data were taken between Nov 6 and 15, 2001 with the CHARA Array 330 m E1-S1 baseline. Some 460 to 830 scans were taken in both directions with the auxiliary PZT, and seeing conditions were fair to poor for these runs (r<sub>0</sub> &asymp; 7 cm).
This procedure yielded a projected separation for each data set, with an intrinsic accuracy of 0.15 - 0.3 mas. This represents an order of magnitude improvement over speckle interferometry techniques. The orbits were refined by a maximum likelihood technique. In the case of 12 Per the semimajor axis obtained was &alpha; = 53.53 mas, compared with the previous orbit of 53.38 mas, a small increase of 0.27%, which implies a mass increase of 0.8%, an insignificant change for this well-established orbit. For Beta Arietis, we find that &alpha; = 35.62 versus the previous orbit's value of 36.00 mas. This is a 1.0% decrease, resulting in a mass decrease of 3.0% for this system.

The OHANA interferometric array will be implemented by linking existing Mauna Kea telescopes with optical fiber. No new facility construction on Mauna Kea is required or planned for OHANA. Fibers will be run through existing cableways. The maximum potential baselines are approximately 800 meters in length. Interferometric operation with good UV coverage will require within the instrument variable optical delay approaching 400 meters. It will be necessary to provide this length of delay within a modest amount of existing laboratory space. An obvious approach is the use of multiple passes
within a short delay line space. This poster investigates possible
multi-pass implementations and related issues of efficiency, cost,
wavefront quality and diffraction. The required optical delay can be
provided at reasonable efficiency and moderate cost. The simpler optical delay for OHANA Phase II, already under construction, is described.

During the 2001 observing season, the CHARA Array was in regular operation for a combined program of science, technical development, test, and commissioning. Interferometric science operations were carried out on baselines up to 330 meters -- the maximum available in the six-telescope array. This poster gives sample results obtained with the approximately north-south telescope pair designated S1-E1. At operating wavelengths in the K band, the 330 m baseline is well suited to diameter determinations for angular diameters in the range 0.6 - 1.2 milliarcseconds. This is a good
range for study of a wide range of hot stars. In this poster, angular
diameters for a set of A,B and F stars are compared to results derived from other sources. These confirm CHARA performance in the range 3-10% in visibility. The normal stars follow a normal spectral type - surface brightness relation, and a classical Be star deviates from the norm by an amount consistent with its apparent colors.

The CHARA Array is a six element optical and near infrared interferometer built by Georgia State University on Mount Wilson in California. It is currently operating in the K and H bands and has the largest baseline (330 m) in operation of any similar instrument in the world. We expect to begin I band operations in 2002. We will present an update of the status of the instrumentation in the Array and set out our plans for the near term expansion of the system.

In this paper we describe the telescope optics, manufacturing tolerances and the geometric alignment procedure of the CHARA telescopes. We also report on our efforts to test and refine the alignment of the telescopes by implementing the curvature sensing method. The results of the first experiments on telescope W1 show that we can get consistent results with this method. We also found a slight distortion caused by the lateral support of the primary mirror.

Phoenix, a high resolution near-infrared spectrograph build by NOAO, was first used on the Gemini South telescope in December 2001. Previously on the Kitt Peak 2.1 and 4 meter telescopes, Phoenix received a new detector, as well as modified refrigeration, mounting, and handling equipment, prior to being sent to Gemini South. Using a two-pixel slit the resolution is ~75,000, making Phoenix the highest resolution infrared spectrograph available on a 6-10 meter class telescope at the current time. Modifications to and performance of the instrument are discussed. Some results on Magellanic cloud stars, brown dwarf stars, premain-sequence objects, and stellar exotica are reviewed briefly.

A unique set of instrument enclosures was implemented as part of an interferometric array now in place atop Mt. Wilson, California. These enclosures were designed in response to project criteria set forth in the planning phases of a new project by the Center for High Angular Resolution Astronomy at Georgia State University. The array is intended for high resolution imaging at optical and infrared wavelengths and is comprised of six 1-m diameter telescopes arranged in a Y-shaped configuration with a maximum baseline of approximately 350 m.

Georgia State University's Center for High Angular Resolution Astronomy (CHARA) is building an interferometric array of telescopes for high resolution imaging at optical and infrared wavelengths. The `CHARA Array' consists of six 1-m diameter telescopes arranged in a Y-shaped configuration with a maximum baseline of approximately 350 m. Construction of the facility will be completed during 2000, and the project will enter a phase in which beam combination subsystems will be brought on line concurrently with initial scientific investigations. This paper provides an update on recent progress, including our reaching the significant milestone of `first fringes' in November 1999. An extensive collection of project technical reports and images are available at our website.

The CHARA Array employs vacuum light pipes between the telescopes and the beam combination area. The complex terrain of the Mt. Wilson site poses interesting problems, with light pipes both underground and suspended up to 10 meters above ground. Telescope to beam-combination distances are up to about 180 meters. The support scheme and alignment strategy will be described.

In order to exploit the interferometric resolution advantage to the utmost, an array with a significant number of telescopes and large (and variable) baselines will be required. Achieving the sensitivity needed for a wide range of science opportunities requires large, AO equipped individual apertures. Dual-beam operation will be needed to support good sky coverage. Phasing of the array for resolved sources can be accomplished with wide-band, pair-wise combination, bootstrapping, and phase closure. For the best sensitivity with maximum field of view, the imaging focus must employ direct optical synthesis of the PSF, while for best sensitivity with reduced field-of-view, pupil densification may be used. The suggested concept, for discussion purposes, consists of 27 telescopes of 3.5-m aperture, distributed in a Cornwell circle configuration. Such a facility would most likely have a cost in the range discussed for a next generation large aperture telescope. The technical readiness is good.

We report on first scientific observations of a few bright late type stars by direct long baseline interferometry in the thermal infrared (3.4 to 4.1 microns) obtained with the TISIS (Thermal Infrared Stellar Interferometric Set-up) experiment of the IOTA (Infrared and Optical Telescope Array) interferometer. Beam combination is provided by a single-mode fluoride glass coupler optimized for operation in that wavelength domain and yielding visibility measurements with 2% typical relative accuracy. First precise estimations of uniform disk diameters for (alpha) Orionis, (alpha) Herculis, o Ceti and R Leonis are presented in the L band. Very large increase (50 to 70%) in apparent angular diameters have been found for the 2 Mira stars o Ceti and R Leonis with respect to previous measurements obtained at shorter infrared wavelengths and same luminosity phase. Extended optically thin close-by dust shells characterized by Infrared Spatial Interferometer measurements are not found to play a significant role in the observed L band intensity distribution. Gas properties are likely to have a greater impact at these wavelengths. Our o Ceti interferometric observations look indeed in good agreement with the presence of very extended circumstellar gas layers (mostly H<SUB>2</SUB>O and SiO) derived from recent Infrared Space Observatory thermal infrared spectral data.

The CHARA array achieved first fringes late last year and is currently being expanded on Mount Wilson CA. This presentation is a follow on from the overview given by Hal McAlister and will give more technical detail on the optical systems, with a focus on the telescopes, the delay lines, the control system, and the beam combining scheme. Combining more than three beams is not a simple problem with no obvious best solution, and we have by no means locked ourselves into a particular design. Preliminary designs will be shown, the first beam combiner will also be discussed along with our plans for future development.

Following extensive development effort, approximately a dozen adaptive optics facilities are now available for research in astronomy, and a similar number is nearing competition or in advanced planning. The scientific productivity, measured by research papers, is rapidly increasing. From a survey of published research and a review of research provisionally discuss the contribution of natural guide star adaptive optics to astronomy. The most active research topics for adaptive optics astronomy have been in solar system studies and in the observation of young stars and star forming regions. The benefit of adaptive optics most prominently exercised in these observations has been high resolution imagery, and the most common area of concern is the point spread function. The scientific success supports the position that adaptive optics will son be required for large telescopes to remain competitive in certain research areas. At the same time, most areas of astronomy research remain untouched by adaptive optics techniques.

We describe a cryogenic, high-resolution spectrograph (Phoenix) for the 1-5 micrometers region. Phoenix is an echelle spectrograph of the near-Littrow over-under configuration without cross dispersion. The foreoptics include Lyot re- imaging, discrete and circular variable order sorting filters, a selection of slits, and optics for post-slit and Lyot imaging. The entire instrument is cooled to 50 K using two closed cycle coolers. The detector is a Hughes-Santa Barbara 512 X 1024 InSb array. Resolution of 65,000 has been obtained. Throughput without slit losses is 13 percent at 2.3 micrometers . Recent results are discussed. Phoenix is a facility instrument of the National Optical Astronomy Observatories and will be available at CTIO, KPNO, and Gemini.

The Center for High Angular Resolution Astronomy (CHARA) at Georgia State University is building an
interferometric array of telescopes for high resolution imaging at optical and infrared wavelengths. The "CHARA Array" will initially consist offive 1-rn diameter telescopes arranged in a Y-shaped configuration with a maximum baseline of approximately 350 m. The facility is being constructed on Mt. Wilson, near Pasadena, California, a site noted for stable atmospheric conditions that often gives rise to exceptional image quality. The Array will be capable of submilliarcsecond imaging and will be devoted to a broad program of science aimed at fundamental stellar astrophysics in the visible and the astrophysics of young stellar objects in the infrared (2.2&mu;m) spectral regions. This project is being funded in approximately 50/50% shares by Georgia State University and the National Science Foundation. The CHARA Array is expected to become operational during 1999. This paper presents a project status report. An extensive collection of project reports and images are available at our website (http://www.chara.gsu.edu).

The telescope requirements of optical interferometry are somewhat different from conventional astronomy. The need for multiple units (in the CHARA case initially five, eventually seven) accentuates the importance of cost control, and at the same time provides opportunity for cost savings by careful procurement and production practices. Modern ideas about telescope enclosures offer significantly reduced dome seeing, but it is difficult to capture these benefits at low cost. The CHARA group has followed a series of design and bid procedures intended to optimize the costperformance of the telescope+enclosures. These have led to a compact but massive telescope design, blending modern and classical features, an unusual mirror blank selection process (directly ompeting several mirror blank technologies) , and a novel telescope enclosure concept which allows a continuous trade between wind protection and natural ventilation. This contribution will review and motivate the design decisions and show the resulting equipment and facilities.

The Center for High Angular Resolution Astronomy (CHARA) at Georgia State University is building an interferometric array of telescopes for high resolution imaging at optical and infrared wavelengths. The 'CHARA Array' will initially consist of five 1-m diameter telescopes arranged in a Y-shaped configuration with a maximum baseline of approximately 350 m. The facility will be located on Mt. Wilson, near Pasadena, California, a site noted for its stable atmoshperic conditions that often gives rise to exceptional image quality. The Array will be capable of submilliarcsecond imaging and will be devoted to a broad program of science aimed at fundamental stellar astrophysics in the visible and the astrophysics of young stellar objects in the infrared (2.2 micrometers ) spectral regions. This project has been supported by the National Sceince Foundation through Phase A feasibility and Phase B preliminary design stages, and NSF awarded 5.6 million dollars towards the construction of the facility in October 1994. Georgia State University is committed to providing an additional 5.8 million dollars in construction funds. The CHARA Array is expected to be operational late this decade. This paper will provide a summary overview of the project.

The Infrared Optical Telescope Array (IOTA) is an interferometric facility currently observing in the near infrared bands at the Smithsonian Institution's Fred Lawrence Whipple Observatory in Arizona. The 45 cm siderostats can be moved on an L-shaped track allowing discrete bases ranging between 5 and 38 m. The capability to combine beams with fiber optics in the K band (2 micrometers &lt;EQ (lambda) &lt;EQ 2.4 micrometers ) has been demonstrated on the Fiber Link Unit for Optical Recombination (FLUOR) at Kitt Peak National Observatory, in which two existing 0.8 m telescopes have been coherently coupled by means of optical fibers. FLUOR is now set as a focal instrument of IOTA. It uses single-mode fluoride glass waveguides and couplers as a substitute for mirrors and beamsplitters to perform beam transportation and recombination. Processing the light in single-mode waveguides offers the possibility to self-calibrate each interferogram against the loss of fringe visibility induced by atmospheric turbulence, thus improving the accuracy of the fringe visibility measurements. The FLUOR unit can be operated as a Mach-Zehnder interferometer to produce zero-baseline spectra used in double-Fourier interferometry to obtain the visibility as a function of wavelength. In the current status, a N-S baseline of 21.2 m is used to observe late-type starts and derive their angular diameters.

The CHARA array is an optical and IR imaging array of seven 1-m aperture telescopes with a Y-shaped configuration contained within a 400-m diameter circle. The facility will be capable of submilliarcsecond imaging and will be devoted to a broad program of science aimed at fundamental stellar astrophysics in the visible and the astrophysics of young stellar objects in the infrared spectral regions. The concept for the array has been carried through Phase A feasibility and Phase B preliminary design stages with funding provided by the National Science Foundation. This paper will provide a progress report on the status of the project.

An astrometric interferometer in space will provide a dramatic improvement in the accuracy with which stellar positions may be measured. The potential and the far ranging impact in science of this capability has deeply impressed the scientific community, with the result that a high priority has been assigned to a mission for precision astrometry. In this talk I will review the origins of the AIM concept, describe the scientific opportunities, and show the relationship to ground capabilities and to other space astronomy missions.

The performance of a phase recovery algorithm developed for speckle data collected using a pupil-plane mask has been investigated for use at near-infrared wavelengths. The method, based on the radio-astronomical self-calibration technique, has been tested alongside a state-of-the-art implementation of the Knox-Thompson scheme using both simulated and real specklegrams. Results indicate that the new procedure is as effective as the Knox-Thompson based image reconstruction scheme and is applicable to a wide range of astrophysically interesting sources.

Construction of a two-telescope Michelson spatial inteferometer to be operated at a nominal wavelength of 2.2 microns in the near-IR began in May 1987. Nearly all of the mechanical, electronic, and optical hardware of the Infrared Michelson Array (IRNMA) is currently in place and has been tested. Proof-of-concept has been demonstrated, and efforts are currently underway to improve the system operation to produce reliable, calibrated fringe visibilities.

Hardware and software improvements to the IR speckle camera are reported. The observing experience obtained during the first year of operation allows a preliminary discussion of exposure times, limiting magnitudes, observing strategies and problems, duty-cycle, data handling, and real-time and off-line processing. The results with this system have also helped to define directions for future developments in high resolution IR imaging.

The optical design of a high-resolution 2-5-micron IR cryogenic echelle spectrometer which is currently under construction at NOAO is described. Special attention is given to the design and the purpose of the four units into which the spectrometer's optic can be divided: the foreoptics unit, the order-separation filter and slit unit, the echelle-collimator unit, and the camera unit. Optical specifications of each of these units are summarized.

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